Systems and computer-implemented methods for a bet exchange. The bet exchange receives bet orders from users and matches bet-for orders with bet-against orders to generate instances of standardized bet contracts. The bet-for orders are bets on a bet event occurring, and bet-against orders are bets on a bet event not occurring. The bet events have a standardized payout amount, which is used to determine a value to transfer to the trader that made the bet-for order when the bet event occurs, or to the trader that made the bet-against order when the bet event does not occur.